KR100646186B1 - Driving apparauts and driving method of plasma display panel - Google Patents

Abstract

A driving device and method of a plasma display panel are provided to minimize halftone noise in applying a gravity center code and to improve the expression performance of gray scales by using a lot of the actual gray scales. A driving device of a plasma display panel(120) includes a VSC(Video Signal Control Circuit) unit(122) receiving a video signal; an inverted gamma correction unit(102A), a halftone processing unit(106), a sub field mapping unit(108), and a data aligning unit(110), which are connected between the VSC unit and the plasma display panel; a waveform generating unit(118) supplying a timing control signal to the plasma display panel; and a full-mapping unit(130) connected between the inverted gamma correction unit and the waveform generating unit. The full-mapping unit selectively supplies at least two lookup tables having different subfield codes, to the waveform generating unit.

Description

Driving device and method of plasma display panel {DRIVING APPARAUTS AND DRIVING METHOD OF PLASMA DISPLAY PANEL}

1 is a perspective view showing a discharge cell structure of a conventional three-electrode AC surface discharge type plasma display panel.

2 is a diagram showing a frame structure of a conventional plasma display panel.

3 is a view illustrating a driving apparatus of a plasma display panel according to an exemplary embodiment of the present invention.

4 is a view showing in detail the full mapping unit of FIG.

5 is a graph showing an optical center according to the GCC method.

6 illustrates subfield mapping according to a basic weighting scheme.

7 illustrates a subfield code according to a GCC and a basic weighting scheme.

8 illustrates subfield mapping according to a small weighting scheme;

9 illustrates subfield mapping according to GCC and basic weighting and small weighting schemes.

<Explanation of symbols for main parts of the drawings>

10: upper substrate 14: upper dielectric layer

16: protective film 18: lower substrate

20X: address electrode 22: lower dielectric layer

24: partition 26: phosphor layer

30Y: scan / sustain electrode 30Z: common sustain electrode

102A and 102B: first and second inverse gamma correction units

104: gain control unit 106: halftone processing unit

108: subfield mapping unit 110: data alignment unit

112: APL detector 118: waveform generator

120: plasma display panel 122: VSC

130: pool mapping unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving apparatus and method for a plasma display panel, and more particularly to a driving method for a plasma display panel to improve image quality.

In general, a plasma display panel (Plasma Display Panel) is an image containing characters or graphics by emitting a phosphor by ultraviolet light of 147nm generated when the discharge of an inert gas such as He + Xe, Ne + Xe or He + Ne + Xe Will be displayed. The plasma display panel is not only thin and large in size, but also greatly improved in image quality due to recent technology development. In particular, the three-electrode AC surface discharge type plasma display panel has advantages of low voltage driving and long life because wall charges are accumulated on the surface during discharge and protect the electrodes from sputtering caused by the discharge.

1 is a perspective view illustrating a discharge cell structure of a general plasma display panel.

Referring to FIG. 1, a discharge cell of a three-electrode AC surface discharge type plasma display panel includes a scan / sustain electrode 30Y and a common sustain electrode 30Z formed on an upper substrate 10, and a lower substrate 18. And formed address electrode 20X. Each of the scan / sustain electrode 30Y and the common sustain electrode 30Z has a line width smaller than the line widths of the transparent electrodes 12Y and 12Z and the transparent electrodes 12Y and 12Z and is formed on one edge of the transparent electrode. (13Y, 13Z).

The transparent electrodes 12Y and 12Z are usually formed on the upper substrate 10 by indium tin oxide (ITO). The metal bus electrodes 13Y and 13Z are usually formed of metals such as chromium (Cr) and formed on the transparent electrodes 12Y and 12Z to reduce voltage drop caused by the transparent electrodes 12Y and 12Z having high resistance. The upper dielectric layer 14 and the passivation layer 16 are stacked on the upper substrate 10 having the scan / sustain electrode 30Y and the common sustain electrode 30Z side by side. In the upper dielectric layer 14, wall charges generated during plasma discharge are accumulated. The protective layer 16 prevents damage to the upper dielectric layer 14 due to sputtering generated during plasma discharge and increases emission efficiency of secondary electrons. As the protective film 16, magnesium oxide (MgO) is usually used.

The lower dielectric layer 22 and the partition wall 24 are formed on the lower substrate 18 on which the address electrode 20X is formed, and the phosphor layer 26 is coated on the surfaces of the lower dielectric layer 22 and the partition wall 24. The address electrode 20X is formed in the direction crossing the scan / sustain electrode 30Y and the common sustain electrode 30Z. The partition wall 24 is formed in parallel with the address electrode 20X to prevent ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells. The phosphor layer 26 is excited by ultraviolet rays generated during plasma discharge to generate visible light of any one of red, green, and blue. An inert mixed gas such as He + Xe, Ne + Xe or He + Ne + Xe for discharging is injected into the discharge space of the discharge cells provided between the upper and lower substrates 10 and 18 and the partition wall 24.

The three-electrode AC surface discharge plasma display panel is driven by dividing one frame into several subfields SF having different emission counts in order to realize gray levels of an image. The subfield SF is divided into an sustain period for implementing gradation according to an address period for selecting a discharge cell and the number of discharges. Here, an erase period for erasing the sustain discharge is added after the sustain period in each subfield SF. For example, when the image is to be displayed with 256 gray levels, a frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields SF1 to SF8 as shown in FIG. In addition, each of the eight subfields SF1 to SF8 is divided into an address period and a sustain period. Here, the reset period and the address period of each subfield are the same for each subfield, while the sustain period and the number of discharges are 2 ⁿ (n = 0,1,2,3,4,5,6,7) in each subfield. Is increased in proportion.

In the conventional plasma display panel driven in this manner, the gray scale is limited by the number of discharges, and thus, various half tone schemes are used to express the insufficient gray scale. Specifically, the gradation representation is currently represented using ten subfields at a driving frequency of 60 Hz. The actual number of gradations that can be represented by the 10 subfields is 1024, but due to the problem of False Contour, all gradations cannot be used and 50 to 60 gradations are selected and used. This method uses the selected gradation to express the gradation to create a gradation between them. However, as the halftone amount increases, noise of a multi-gradation expression is generated on the screen, and there is a problem that false contour occurs when the real tone is increased to reduce the halftone amount.

Accordingly, an object of the present invention is to provide an apparatus and method for driving a plasma display panel that can improve image quality.

In order to achieve the above object, a driving apparatus of a plasma display panel according to an embodiment of the present invention includes a video signal control circuit unit to which a video signal is input; An inverse gamma correction unit and a halftone processing unit connected between the video signal control circuit unit and the plasma display panel; A subfield mapping unit and a data sorting unit; A waveform generator for supplying a timing control signal to the plasma display panel; And a full mapping unit connected between the inverse gamma correction unit and the waveform generation unit, wherein the full mapping unit selectively supplies at least two lookup tables each having a differently generated subfield code to the waveform generation unit. It is done.

The full mapping unit includes: a first lookup table having a subfield code created by a first scheme; A second lookup table having a subfield code created by a second scheme different from the first scheme; And a weighting selector for selecting any one of the first and second lookup tables to compare the change of the grayscale value supplied from the inverse gamma correction unit with a predetermined threshold value and to supply the waveform to the waveform generator. It is done.

When the gray scale is represented by N subfields, the first scheme generates a first subfield code according to a gravity center code scheme for generating grayscale values according to a light center.

The second method is a method of adding up the first subfield code and a second subfield code generated by applying a value different from a mapping value applied in the first method to the second half of the N subfields. do.

The weighting selector supplies a second lookup table to the waveform generator when the increase of the gradation value is greater than the predetermined threshold value, and supplies the first lookup table to the waveform generator when the weight value is smaller than the threshold value. Characterized in that.

A method of driving a plasma display panel according to an exemplary embodiment of the present invention includes generating an inverse gamma corrected gray value from a video signal; Comparing the gamma corrected gray value with a predetermined threshold value; Selecting one of at least two lookup tables having subfield codes written differently according to the comparison with the threshold value; And supplying the selected lookup table to a waveform generator.

The at least two lookup tables may be configured to generate a first subfield code according to a gravity center code method for generating grayscale values according to a light center when grayscales are represented by N subfields (N is a natural number). A first lookup table created by; And a second lookup created by a second method of adding the first subfield code and a second subfield code generated by applying a value different from the mapping value applied in the first method to the second half of the N subfields. It characterized in that it comprises a table.

Other objects and features of the present invention in addition to the above objects will be apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 3 to 9.

3 is a diagram illustrating a driving apparatus of a plasma display panel according to an exemplary embodiment of the present invention.

Referring to FIG. 3, a driving apparatus of a plasma display panel according to an exemplary embodiment of the present invention includes a video signal control circuit (VSC) 122 through which a video signal is input, and a VSC ( 122, the inverse gamma correction unit 102, the halftone processing unit 106, the subfield mapping unit 108 and the data alignment unit 110 connected between the plasma display panel 120, the reset pulse and the sustain pulse And a waveform generator 118 for supplying a timing control signal to the plasma display panel 120, and a full mapping unit 130 connected between the inverse gamma correction unit 102 and the waveform generator 118. do.

The VSC 122 samples and digitizes the analog video signal according to the clock signal.

The inverse gamma correction unit 102 inversely gamma corrects the digital video signal from the VSC 122 to linearly convert the luminance value according to the gray value of the video signal.

The halftone processing unit 106 forms the intermediate gradation between the real gradation and the real gradation to fill the gradation to diversify the gradation expression. The halftone processing unit 106 uses a dithering method and an error diffusion method. The halftone processing unit 106 generates an intermediate grayscale from the grayscale value supplied from the inverse gamma correction unit 102 and adds the halftone to the subfield mapping unit 108.

The subfield mapping unit 108 maps the data input from the halftone processing unit 106 to prestored subfields and supplies the data to the data alignment unit 110 for each subfield.

The data aligning unit 110 supplies the video data input from the subfield mapping unit 108 to a data driving integrated circuit (hereinafter referred to as “IC”) of the plasma display panel 120. The data driving IC is connected to the data electrodes of the plasma display panel 120 to latch data input from the data alignment unit 110 by one horizontal line, and then supply the latched data to the data electrodes in units of one horizontal period. do.

The waveform generator 118 generates a timing control signal for driving the plasma display panel 120 in response to a signal input from the APL detector 118, and outputs the timing control signal to a data driver IC, a scan driver IC, and a sustain signal. Supply to drive IC. The scan driving IC is connected to the scan electrodes of the plasma display panel 120 orthogonal to the data electrodes to sequentially supply scan pulses to the scan electrodes in response to a timing control signal input from the waveform generator 118. During the sustain period, sustain pulses are simultaneously supplied to the scan electrodes. The sustain driving IC supplies sustain pulses to the sustain electrodes formed on the plasma display panel 120 to be in parallel with the scan electrodes and to be paired with the scan electrodes.

The full mapping unit 130 selects a sustain table from different lookup tables according to the real gray value corrected by the inverse gamma correction unit 102 and supplies the sustain table to the waveform generator 118 to improve image quality. As shown in FIG. 4, the full mapping unit 130 includes a first lookup table 132 generated by a Gravity Center Code (GCC) method according to a light center, a GCC method, and a small weighting method. And a weighting selector 136 for selecting the first and second lookup tables 132 and 134 generated by the application of small weighting.

The first lookup table 132 is based on the existing base weighting of 50 to 60 mappings in which the optical axis can be smoothly changed from the GCC graph shown in FIG. 5 when the gray scale is represented using 10 subfields. ) To calculate the center of gravity and select the actual gradation. The selected real gradation is mapped to each subfield, for example, as shown in FIG. The remaining insufficient gray levels are generated through halftones to generate subfield codes. The subfield code generated in this manner may be represented as the first lookup table 132 as shown in FIG. 7. The first lookup table 132 has a mapping code centered on the left triangle area, and the right triangle area is empty.

The second lookup table 134 is a small weighting method in the sixth to tenth subfields sf6 to sf10 in the subfield mapping created from the basic weighting method used to generate the first lookup table 132. By further applying the method, two mapping methods are applied to the sixth to tenth subfields sf6 to sf10 as shown in FIG. 8. Accordingly, the second lookup table 134 is newly added to the subfield codes generated by the basic weighting method used to generate the first lookup table 132 and the sixth to tenth subfields sf6 to sf10. The subfield codes generated by the applied small weighting scheme are combined and appear as shown in FIG. 9. Here, since the real gray value is added by the small weighting method, the real gray level is added to a region having many halftone applications, and thus the step difference between the real gray levels is reduced.

The weight selector 136 uses the first lookup table 132 generated by the basic weighting for the subfield codes corresponding to the sixth to tenth subfields sf6 to sf10, or the first generated by the small weighting. 2 Select whether to use the lookup table 134. The weight selector 136 is designed to apply the second lookup table 134 where the gray value changes by more than a predetermined threshold, and the predetermined size is determined by the experimental value. That is, since the change in the gray scale value is different depending on the number of subfields used, the size of each plasma display panel, and the difference in resolution to be supported, the predetermined threshold value may be set differently. In addition, this threshold value is generally applicable at the time of subfield switching because the gray level changes greatly at the point where the subfield is switched.

In the driving method of the driving apparatus of the plasma display panel having the structure as described above, the halftone processing unit 106 and the weighting selector 136 first convert the gray level value corrected by the inverse gamma correction unit 102. To feed.

The weight selector 136 compares the supplied gray value with a threshold value, selects the second lookup table 134 when it is determined that the gray value has changed by more than the threshold value, and selects a change below the threshold value. If it is determined to have, the first lookup table 132 is selected and supplied to the waveform generator 118.

The waveform generator 118 may be configured by considering one of the first and second lookup tables 132 and 134 supplied from the weighting selector 136 and the subfield mapping supplied from the subfield mapping unit 108. It is to control the discharge of.

The driving apparatus and method of the plasma display panel according to the embodiment of the present invention generate the subfield code by applying the sustain weight to the basic weighting method and the small weighting method, so that the mapping has not been used by the basic weighting method. With the addition of code, you can make the best use of the mapping of subfield codes. In addition, since the code is added in a small weighting method in which weighting is additionally applied to subfields in the latter half of the subfields selected in the basic weighting, the influence on the optical center can be minimized. That is, the driving apparatus and method of the plasma display panel according to the embodiment of the present invention can simultaneously obtain the effect of applying the gravity center code while using more real grayscale.

Here, although the small weighting method of the full mapping unit 130 according to an embodiment of the present invention is selected by using a mapping value applied to the subfield of the latter half in the basic weighting method, it may be applied to other subfields as necessary. Do. That is, the small weighting scheme may generate a subfield code by applying a value different from the mapping value applied to the basic weighting scheme. In addition, although the driving apparatus and driving method of the plasma display panel according to an exemplary embodiment of the present invention have been described based on 10 subfields, it is obvious that the present invention can be applied to N subfields (where N is a natural number).

As described above, the driving apparatus and driving method of the plasma display panel according to the present invention can minimize the generation of halftone noise when applying the gravity center code, and the actual grayscale is used more substantially than before. Gradation expression can be improved.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (7)

A video signal control circuit unit to which a video signal is input; An inverse gamma correction unit, a halftone processing unit, a subfield mapping unit, and a data alignment unit connected between the video signal control circuit unit and the plasma display panel; A waveform generator for supplying a timing control signal to the plasma display panel; And A full mapping unit connected between the inverse gamma correction unit and the waveform generation unit, And the full mapping unit selectively supplies at least two lookup tables each having a differently generated subfield code to the waveform generator. The method of claim 1, The pool mapping unit A first lookup table having a subfield code created by the first scheme; A second lookup table having a subfield code created by a second scheme different from the first scheme; And And a weighting selector for selecting one of the first and second lookup tables to compare the change of the grayscale value supplied from the inverse gamma correction unit with a predetermined threshold value and supply the selected one to the waveform generator. The driving device of the plasma display panel. The method of claim 2, The first method When the gray scale is represented by the N subfields, the first subfield code is generated according to a gravity center code method for generating grayscale values according to the optical center. The method of claim 2, The second method And a second subfield code generated by applying the first subfield code and a second subfield code generated by applying a value different from the mapping value applied in the first method to the second half of the N subfields. Drive system. The method of claim 2, The weight selector And when the increase of the gradation value is greater than the predetermined threshold, supplying a second lookup table to the waveform generator, and when smaller than the threshold, supplying a first lookup table to the waveform generator. A driving device of the plasma display panel. Generating an inverse gamma corrected gray value from the video signal; Comparing the gamma corrected gray value with a predetermined threshold value; Selecting one of at least two lookup tables having subfield codes written differently according to the comparison with the threshold value; And And supplying the selected lookup table to a waveform generator. The method of claim 6, The at least two lookup tables A first lookup table created by a first method of generating a first subfield code according to a gravity center code method of generating grayscale values according to a light center when N (N is a natural number) subfields; And A second lookup table created by a second method of adding the first subfield code and a second subfield code generated by applying a value different from the mapping value applied in the first method to the second half of the N subfields; Method of driving a plasma display panel comprising a.

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